Waterflooding has been practiced as a secondary recovery mechanism for many years with no regard to the composition of the injected brine. However, in the last decade, there has been an interest to understand the impact of the injected water composition and the low salinity waterflooding (LSWF) in oil recovery. LSWF has been investigated through various laboratory tests as a promising method for improving oil recovery in carbonate reservoirs. These experiments showed diverse mechanisms and results. In this study, a comprehensive review and analysis for results of more than 300 carbonate core flood experiments from published work were performed to investigate the effects of several parameters (injected water, oil, and rock properties along with the temperature) on oil recovery from carbonate rock. The analysis of the results showed that the water composition is the key parameter for successful waterflooding (WF) projects in the carbonate rocks. However, the salinity value of the injected water seems to have a negligible effect on oil recovery in both secondary and tertiary recovery stages. The study indicated that waterflooding with optimum water composition can improve oil recovery up to 30% of the original oil in place. In addition, the investigation showed that changing water salinity from LSWF to high salinity waterflooding can lead to an incremental oil recovery of up to 18% in the tertiary recovery stage. It was evident that applying the optimum composition in the secondary recovery stage is more effective than applying it in the tertiary recovery stage. Furthermore, the key parameters of the injected water and rock properties in secondary and tertiary recovery stages were studied using Fractional Factorial Design. The results revealed that the concentrations of Mg2+, Na+, K+, and Cl− in the injected water are the greatest influence parameters in the secondary recovery stage. However, the most dominant parameters in the tertiary recovery stage are the rock minerals and the concentration of K+, HCO3−, and SO42− in the injected water. In addition, it appears that the anhydrite percentage in the carbonate reservoirs may be an effective parameter in the tertiary WF. Also, there are no clear relations between the incremental oil recovery and the oil properties (total acid number or total base number) in both secondary and tertiary recovery stages. In addition, the results of the analysis showed an incremental oil recovery in all ranges of the studied flooding temperatures. The findings of this study can help to establish guidelines for screening and designing optimum salinity and composition for WF projects in carbonate reservoirs.

Waterflooding has been applied for many years as secondary recovery method with no or little regard to the effect of the injected water salinity on oil recovery. However, in the last decade, there has been an increasing interest in understanding the effects of changing injected water salinity on reservoir performance. The potential of low-salinity waterflooding (LSWF) has been studied in sandstone reservoirs by numerous core-flooding experiments. These experiments have shown diverse results. This paper aims to investigate the effects of changing water salinity on oil recovery. A comprehensive review and analysis of the results of more than 500 core-flood experiments from published work were investigated to study the effects of several parameters such as clay content, clay type, and temperature on oil recovery. The relation between incremental oil recovery and sodium adsorption ratio SAR, and exchangeable sodium percentage (ESP) parameters which control clay swelling was illustrated. The analysis of the results revealed that there is an optimum composition and optimum salinity for waterflooding in secondary flooding stage. However, for tertiary flooding stage, the results showed that the controlling factor may be not decreasing the salinity but rather changing the salinity (e.g., either increasing or decreasing) with minor improvement in oil recovery. It was clear also that applying the optimum salinity in the secondary recovery stage is more effective than applying it in the tertiary recovery stage. This study aims to develop important guidelines for screening and designing optimum salinity for waterflooding projects in sandstone reservoirs.

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Ultrasonic waves have been used for improved oil recovery especially from the marginal well in so many area all over the world. The main mechanisms of the seismic pulses from ultrasonic waves is to supply oil molecules by energy to overcome capillary forces there by restructuring the relative permeability curves increasing the oil mobility. Monitoring these changes is very important for increasing the mobility of oil even after residual oil saturation achieved by water flooding.The present work discusses and investigates the laboratory effects of ultrasonic waves on the relative permeability curves by measuring it before and after applying the pulse waves. Six core samples was used from Egyptian homogeneous reservoirs, these cores are sandstone and carbonate, their permeabilities range from 67 to 460 md. In this technique. Acoustic ultrasonic waves of 500 KHZ was applied in cores is this research. At this frequency, the fluid vibrates out of phase with the solid and is forced out through the pore structure in the agglomerate. This relative fluid motion to exert high viscous stresses at the particle-particle contact points which leads to fracture of the agglomerate and the dispersion of the individual particles.The interaction of the generated waves with the fluids in the pores causes changes in relative permeability of the rock to oil and water, which may lead to improve the rate of oil production. Therefore, the results showed that applying ultrasonic waves has a higher effect in low permeability reservoirs (75 md to 460 md) and can mobilize additional quantity of crude oil. The fractional flow curve changes are also addressed and analyzed after ultrasonic wave applications.The ultimate aim of this research is to investigate the effect of the ultrasonic wave as new proposed method to improve oil recovery by changing the relative permeability curves of the reservoirs. Moreover, it can be used to determine and investigate the recovery mechanisms for improving oil recovery.

Ultrasonic waves have been used for improved oil recovery especially from the marginal well in so many areas all over the world. The main mechanism is to supply oil molecules by energy to overcome capillary forces there by restructuring the relative permeability curves and increasing the oil mobility. Monitoring these changes is very important for increasing the oil mobility even after residual oil saturation achieved. The present work investigates the laboratory effects of ultrasonic waves on the relative permeability curves. Five sandstone and carbonate cores were used from Egyptian reservoirs. Their permeabilities range from 67 to 460 md. Acoustic ultrasonic waves of 500 KHZ have been applied. At this frequency, the fluid vibrates out of phase with the solid and is forced out through the pore structure in the agglomerate. This relative fluid motion exerts high viscous stresses at the particle-particle contact points which leads to fracture of the agglomerate and the dispersion of the individual particles. This interaction causes changes in relative permeability of the rock to oil and water. Therefore, the results showed that applying ultrasonic waves has a higher effect in permeability reservoirs (76 md to 460 md) and can mobilize additional quantity of crude oil. The fractional flow curve changes are also addressed and analyzed after wave applications. The aim of this research is to investigate the effect of the ultrasonic wave as a new proposed method to improve oil recovery by changing the relative permeability curves of the reservoirs.